Oosting J, Struijker-Boudier H A, Janssen B J
Department of Pharmacology, Universiteit Maastricht, The Netherlands.
J Hypertens. 1997 Apr;15(4):401-10. doi: 10.1097/00004872-199715040-00011.
To examine the influence of the autonomic nervous system on ultradian and circadian rhythms of blood pressure, heart rate and baroreflex sensitivity of heart rate (BRS) in spontaneously hypertensive rats (SHR).
Spontaneous fluctuations in blood pressure, heart rate and BRS in SHR were recorded continuously for 24 h using a computerized system and compared with those in Wistar-Kyoto (WKY) rats. Furthermore, 24 h recordings were performed in SHR during cardiac autonomic blockade by metoprolol and methyl-atropine, vascular autonomic blockade by prazosin, ganglionic blockade by hexamethonium and vagal stimulation by a low dose of scopolamine. The magnitudes of the ultradian fluctuations in blood pressure, heart rate and BRS were assessed by wide-band spectral analysis techniques.
The BRS was lower in SHR than it was in WKY rats throughout the 24 h cycle. In both strains high values were found during the light, resting period, whereas low values were found during the first hours of the dark, active period. The circadian rhythmicity of the blood pressure in SHR was abolished completely during the infusions of prazosin and hexamethonium. In contrast, the circadian rhythmicities of the blood pressure and heart rate were not altered by infusions of metoprolol, methyl-atropine and the low dose of scopolamine. Power spectra of the blood pressure and heart rate lacked predominant peaks at ultradian frequencies and showed 1/f characteristics. In the absence of autonomic tone, the ultradian fluctuations in heart rate, but not in blood pressure, were decreased. The ultradian BRS spectra had no 1/f shape, but showed a major peak at approximately equal to 20 min for 71% of the WKY rats and 42% of the SHR.
The influence of the autonomic nervous system on the blood pressure and heart rats in SHR is frequency-dependent. The circadian, but not ultradian, blood pressure rhythmicity is controlled by vascular autonomic activity. Conversely, the circadian, but not ultradian, heart rate rhythmicity is independent of autonomic tone. In rats, just as in humans, the trough in baroreflex sensitivity occurred after the sleeping period, when locomotor activity is resumed.
研究自主神经系统对自发性高血压大鼠（SHR）血压、心率的超日节律和昼夜节律以及心率压力反射敏感性（BRS）的影响。
使用计算机系统连续记录SHR血压、心率和BRS的自发波动24小时，并与Wistar-Kyoto（WKY）大鼠进行比较。此外，在美托洛尔和甲基阿托品进行心脏自主神经阻滞、哌唑嗪进行血管自主神经阻滞、六甲铵进行神经节阻滞以及低剂量东莨菪碱进行迷走神经刺激期间，对SHR进行24小时记录。通过宽带频谱分析技术评估血压、心率和BRS超日波动的幅度。
在整个24小时周期内，SHR的BRS均低于WKY大鼠。在两个品系中，白天休息期数值较高，而在黑暗活跃期的最初几个小时数值较低。在输注哌唑嗪和六甲铵期间，SHR血压的昼夜节律完全消失。相比之下，输注美托洛尔、甲基阿托品和低剂量东莨菪碱并未改变血压和心率的昼夜节律。血压和心率的功率谱在超日频率处缺乏主导峰值，并呈现1/f特征。在无自主神经张力的情况下，心率的超日波动减小，但血压的超日波动未减小。超日BRS谱不具有1/f形状，但71%的WKY大鼠和42%的SHR在约20分钟处显示一个主要峰值。
自主神经系统对SHR血压和心率的影响具有频率依赖性。昼夜血压节律受血管自主神经活动控制，而非超日血压节律。相反，昼夜心率节律独立于自主神经张力，而非超日心率节律。在大鼠中，与人类一样，压力反射敏感性的低谷出现在睡眠期之后，即运动活动恢复时。
